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.Dd $Mdocdate: April 18 2014 $
.Dt PF 4
.Os
.Sh NAME
.Nm pf
.Nd packet filter
.Sh SYNOPSIS
.Cd "pseudo-device pf"
.Sh DESCRIPTION
Packet filtering takes place in the kernel.
A pseudo-device,
.Pa /dev/pf ,
allows userland processes to control the
behavior of the packet filter through an
.Xr ioctl 2
interface.
There are commands to enable and disable the filter, load rulesets,
add and remove individual rules or state table entries,
and retrieve statistics.
The most commonly used functions are covered by
.Xr pfctl 8 .
.Pp
Manipulations like loading a ruleset that involve more than a single
.Xr ioctl 2
call require a so-called
.Em ticket ,
which prevents the occurrence of
multiple concurrent manipulations.
.Pp
Fields of
.Xr ioctl 2
parameter structures that refer to packet data (like
addresses and ports) are generally expected in network byte-order.
.Pp
Rules and address tables are contained in so-called
.Em anchors .
When servicing an
.Xr ioctl 2
request, if the anchor field of the argument structure is empty,
the kernel will use the default anchor (i.e., the main ruleset)
in operations.
Anchors are specified by name and may be nested, with components
separated by
.Sq /
characters, similar to how file system hierarchies are laid out.
The final component of the anchor path is the anchor under which
operations will be performed.
Anchor names with characters after the terminating null byte are
considered invalid; if used in an ioctl,
.Er EINVAL
will be returned.
.Sh IOCTL INTERFACE
.Nm
supports the following
.Xr ioctl 2
commands, available through
.In net/pfvar.h :
.Bl -tag -width xxxxxx
.It Dv DIOCSTART
Start the packet filter.
.It Dv DIOCSTOP
Stop the packet filter.
.It Dv DIOCADDRULE Fa "struct pfioc_rule *pr"
.Bd -literal
struct pfioc_rule {
	u_int32_t	action;
	u_int32_t	ticket;
	u_int32_t	nr;
	char		anchor[MAXPATHLEN];
	char		anchor_call[MAXPATHLEN];
	struct pf_rule	rule;
};
.Ed
.Pp
Add
.Va rule
at the end of the inactive ruleset.
This call requires a
.Va ticket
obtained through a preceding
.Dv DIOCXBEGIN
call.
The optional
.Va anchor
name indicates the anchor in which to append the rule.
.Va nr
and
.Va action
are ignored.
.It Dv DIOCADDQUEUE Fa "struct pfioc_queue *q"
Add a queue.
.Bd -literal
struct pfioc_queue {
	u_int32_t		ticket;
	u_int			nr;
	struct pf_queuespec	queue;
};
.Ed
.It Dv DIOCGETRULES Fa "struct pfioc_rule *pr"
Get a
.Va ticket
for subsequent
.Dv DIOCGETRULE
calls and the number
.Va nr
of rules in the active ruleset.
.It Dv DIOCGETRULE Fa "struct pfioc_rule *pr"
Get a
.Va rule
by its number
.Va nr
using the
.Va ticket
obtained through a preceding
.Dv DIOCGETRULES
call.
If
.Va action
is set to
.Dv PF_GET_CLR_CNTR ,
the per-rule statistics on the requested rule are cleared.
.It Dv DIOCGETQUEUES Fa "struct pfioc_queue *pq"
Get a
.Va ticket
for subsequent
.Dv DIOCGETQUEUE
calls and the number
.Va nr
of queues in the active list.
.It Dv DIOCGETQUEUE Fa "struct pfioc_queue *pq"
Get the queueing discipline
by its number
.Va nr
using the
.Va ticket
obtained through a preceding
.Dv DIOCGETQUEUES
call.
.It Dv DIOCGETQSTATS Fa "struct pfioc_qstats *pq"
Get the statistics on a queue.
.Bd -literal
struct pfioc_qstats {
	u_int32_t	 	 ticket;
	u_int32_t	 	 nr;
	struct pf_queuespec	 queue;
	void			*buf;
	int		 	 nbytes;
};
.Ed
.Pp
This call fills in a pointer to the buffer of statistics
.Va buf ,
of length
.Va nbytes ,
for the queue specified by
.Va nr .
.It Dv DIOCGETRULESETS Fa "struct pfioc_ruleset *pr"
.Bd -literal
struct pfioc_ruleset {
	u_int32_t	 nr;
	char		 path[MAXPATHLEN];
	char		 name[PF_ANCHOR_NAME_SIZE];
};
.Ed
.Pp
Get the number
.Va nr
of rulesets (i.e., anchors) directly attached to the anchor named by
.Va path
for use in subsequent
.Dv DIOCGETRULESET
calls.
Nested anchors, since they are not directly attached to the given
anchor, will not be included.
This ioctl returns
.Er EINVAL
if the given anchor does not exist.
.It Dv DIOCGETRULESET Fa "struct pfioc_ruleset *pr"
Get a ruleset (i.e., an anchor)
.Va name
by its number
.Va nr
from the given anchor
.Va path ,
the maximum number of which can be obtained from a preceding
.Dv DIOCGETRULESETS
call.
This ioctl returns
.Er EINVAL
if the given anchor does not exist or
.Er EBUSY
if another process is concurrently updating a ruleset.
.It Dv DIOCADDSTATE Fa "struct pfioc_state *ps"
Add a state entry.
.Bd -literal
struct pfioc_state {
	struct pfsync_state	state;
};
.Ed
.It Dv DIOCGETSTATE Fa "struct pfioc_state *ps"
Extract the entry identified by the
.Va id
and
.Va creatorid
fields of the
.Va state
structure from the state table.
.It Dv DIOCKILLSTATES Fa "struct pfioc_state_kill *psk"
Remove matching entries from the state table.
This ioctl returns the number of killed states in
.Va psk_killed .
.Bd -literal
struct pfioc_state_kill {
	struct pf_state_cmp	psk_pfcmp;
	sa_family_t		psk_af;
	int			psk_proto;
	struct pf_rule_addr	psk_src;
	struct pf_rule_addr	psk_dst;
	char			psk_ifname[IFNAMSIZ];
	char			psk_label[PF_RULE_LABEL_SIZE];
	u_int			psk_killed;
	u_int16_t		psk_rdomain;
};
.Ed
.It Dv DIOCCLRSTATES Fa "struct pfioc_state_kill *psk"
Clear all states.
It works like
.Dv DIOCKILLSTATES ,
but ignores all fields of the
.Vt pfioc_state_kill
structure, except
.Va psk_ifname .
.It Dv DIOCGETSTATUS Fa "struct pf_status *s"
Get the internal packet filter statistics.
.Bd -literal
struct pf_status {
	u_int64_t	counters[PFRES_MAX];
	u_int64_t	lcounters[LCNT_MAX];	/* limit counters */
	u_int64_t	fcounters[FCNT_MAX];
	u_int64_t	scounters[SCNT_MAX];
	u_int64_t	pcounters[2][2][3];
	u_int64_t	bcounters[2][2];
	u_int64_t	stateid;
	time_t		since;
	u_int32_t	running;
	u_int32_t	states;
	u_int32_t	src_nodes;
	u_int32_t	debug;
	u_int32_t	hostid;
	u_int32_t	reass;			/* reassembly */
	char		ifname[IFNAMSIZ];
	u_int8_t	pf_chksum[MD5_DIGEST_LENGTH];
};
.Ed
.It Dv DIOCCLRSTATUS
Clear the internal packet filter statistics.
.It Dv DIOCNATLOOK Fa "struct pfioc_natlook *pnl"
Look up a state table entry by source and destination addresses and ports.
.Bd -literal
struct pfioc_natlook {
	struct pf_addr	 saddr;
	struct pf_addr	 daddr;
	struct pf_addr	 rsaddr;
	struct pf_addr	 rdaddr;
	u_int16_t	 rdomain;
	u_int16_t	 rrdomain;
	u_int16_t	 sport;
	u_int16_t	 dport;
	u_int16_t	 rsport;
	u_int16_t	 rdport;
	sa_family_t	 af;
	u_int8_t	 proto;
	u_int8_t	 direction;
};
.Ed
.Pp
This was primarily used to support transparent proxies with rdr-to rules.
New proxies should use divert-to rules instead.
These do not require access to the privileged
.Pa /dev/pf
device and preserve the original destination address for
.Xr getsockname 2 .
For
.Dv SOCK_DGRAM
sockets, the
.Xr ip 4
socket options
.Dv IP_RECVDSTADDR
and
.Dv IP_RECVDSTPORT
can be used to retrieve the destination address and port.
.It Dv DIOCSETDEBUG Fa "u_int32_t *level"
Set the debug level.
See the
.Xr syslog 3
man page for a list of valid debug levels.
.It Dv DIOCGETSTATES Fa "struct pfioc_states *ps"
Get state table entries.
.Bd -literal
struct pfioc_states {
	int	ps_len;
	union {
		caddr_t		     psu_buf;
		struct pfsync_state *psu_states;
	} ps_u;
#define ps_buf		ps_u.psu_buf
#define ps_states	ps_u.psu_states
};
.Ed
.Pp
If
.Va ps_len
is non-zero on entry, as many states as possible that can fit into this
size will be copied into the supplied buffer
.Va ps_states .
On exit,
.Va ps_len
is always set to the total size required to hold all state table entries
(i.e., it is set to
.Li sizeof(struct pfsync_state) * nr ) .
.It Dv DIOCCHANGERULE Fa "struct pfioc_rule *pcr"
Add or remove the
.Va rule
in the ruleset specified by
.Va rule.action .
.Pp
The type of operation to be performed is indicated by
.Va action ,
which can be any of the following:
.Bd -literal
enum	{ PF_CHANGE_NONE, PF_CHANGE_ADD_HEAD, PF_CHANGE_ADD_TAIL,
	  PF_CHANGE_ADD_BEFORE, PF_CHANGE_ADD_AFTER,
	  PF_CHANGE_REMOVE, PF_CHANGE_GET_TICKET };
.Ed
.Pp
.Va ticket
must be set to the value obtained with
.Dv PF_CHANGE_GET_TICKET
for all actions except
.Dv PF_CHANGE_GET_TICKET .
.Va anchor
indicates to which anchor the operation applies.
.Va nr
indicates the rule number against which
.Dv PF_CHANGE_ADD_BEFORE ,
.Dv PF_CHANGE_ADD_AFTER ,
or
.Dv PF_CHANGE_REMOVE
actions are applied.
.It Dv DIOCSETTIMEOUT Fa "struct pfioc_tm *pt"
.Bd -literal
struct pfioc_tm {
	int		 timeout;
	int		 seconds;
};
.Ed
.Pp
Set the state timeout of
.Va timeout
to
.Va seconds .
The old value will be placed into
.Va seconds .
For possible values of
.Va timeout ,
consult the
.Dv PFTM_*
values in
.In net/pfvar.h .
.It Dv DIOCGETTIMEOUT Fa "struct pfioc_tm *pt"
Get the state timeout of
.Va timeout .
The value will be placed into the
.Va seconds
field.
.It Dv DIOCCLRRULECTRS
Clear per-rule statistics.
.It Dv DIOCSETLIMIT Fa "struct pfioc_limit *pl"
Set the hard limits on the memory pools used by the packet filter.
.Bd -literal
struct pfioc_limit {
	int		index;
	unsigned	limit;
};

enum	{ PF_LIMIT_STATES, PF_LIMIT_SRC_NODES, PF_LIMIT_FRAGS,
	  PF_LIMIT_TABLES, PF_LIMIT_TABLE_ENTRIES, PF_LIMIT_MAX };
.Ed
.It Dv DIOCGETLIMIT Fa "struct pfioc_limit *pl"
Get the hard
.Va limit
for the memory pool indicated by
.Va index .
.It Dv DIOCRCLRTABLES Fa "struct pfioc_table *io"
Clear all tables.
All the ioctls that manipulate radix tables
use the same structure described below.
For
.Dv DIOCRCLRTABLES ,
.Va pfrio_ndel
contains on exit the number of tables deleted.
.Bd -literal
struct pfioc_table {
	struct pfr_table	 pfrio_table;
	void			*pfrio_buffer;
	int			 pfrio_esize;
	int			 pfrio_size;
	int			 pfrio_size2;
	int			 pfrio_nadd;
	int			 pfrio_ndel;
	int			 pfrio_nchange;
	int			 pfrio_flags;
	u_int32_t		 pfrio_ticket;
};
#define pfrio_exists    pfrio_nadd
#define pfrio_nzero     pfrio_nadd
#define pfrio_nmatch    pfrio_nadd
#define pfrio_naddr     pfrio_size2
#define pfrio_setflag   pfrio_size2
#define pfrio_clrflag   pfrio_nadd
.Ed
.It Dv DIOCRADDTABLES Fa "struct pfioc_table *io"
Create one or more tables.
On entry,
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_table
containing at least
.Vt pfrio_size
elements.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_table .
On exit,
.Va pfrio_nadd
contains the number of tables effectively created.
.Bd -literal
struct pfr_table {
	char		pfrt_anchor[MAXPATHLEN];
	char		pfrt_name[PF_TABLE_NAME_SIZE];
	u_int32_t	pfrt_flags;
	u_int8_t	pfrt_fback;
};
.Ed
.It Dv DIOCRDELTABLES Fa "struct pfioc_table *io"
Delete one or more tables.
On entry,
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_table
containing at least
.Vt pfrio_size
elements.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_table .
On exit,
.Va pfrio_ndel
contains the number of tables effectively deleted.
.It Dv DIOCRGETTABLES Fa "struct pfioc_table *io"
Get the list of all tables.
On entry,
.Va pfrio_buffer[pfrio_size]
contains a valid writeable buffer for
.Vt pfr_table
structures.
On exit,
.Va pfrio_size
contains the number of tables written into the buffer.
If the buffer is too small, the kernel does not store anything but just
returns the required buffer size, without error.
.It Dv DIOCRGETTSTATS Fa "struct pfioc_table *io"
This call is like
.Dv DIOCRGETTABLES
but is used to get an array of
.Vt pfr_tstats
structures.
.Bd -literal
struct pfr_tstats {
	struct pfr_table pfrts_t;
	u_int64_t	 pfrts_packets
			     [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
	u_int64_t	 pfrts_bytes
			     [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
	u_int64_t	 pfrts_match;
	u_int64_t	 pfrts_nomatch;
	time_t		 pfrts_tzero;
	int		 pfrts_cnt;
	int		 pfrts_refcnt[PFR_REFCNT_MAX];
};
#define pfrts_name	 pfrts_t.pfrt_name
#define pfrts_flags	 pfrts_t.pfrt_flags
.Ed
.It Dv DIOCRCLRTSTATS Fa "struct pfioc_table *io"
Clear the statistics of one or more tables.
On entry,
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_table
containing at least
.Vt pfrio_size
elements.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_table .
On exit,
.Va pfrio_nzero
contains the number of tables effectively cleared.
.It Dv DIOCRCLRADDRS Fa "struct pfioc_table *io"
Clear all addresses in a table.
On entry,
.Va pfrio_table
contains the table to clear.
On exit,
.Va pfrio_ndel
contains the number of addresses removed.
.It Dv DIOCRADDADDRS Fa "struct pfioc_table *io"
Add one or more addresses to a table.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_addr
containing at least
.Vt pfrio_size
elements to add to the table.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_addr .
On exit,
.Va pfrio_nadd
contains the number of addresses effectively added.
.Bd -literal
struct pfr_addr {
	union {
		struct in_addr	 _pfra_ip4addr;
		struct in6_addr	 _pfra_ip6addr;
	}		 pfra_u;
	char		 pfra_ifname[IFNAMSIZ];
	u_int32_t	 pfra_states;
	u_int16_t	 pfra_weight;
	u_int8_t	 pfra_af;
	u_int8_t	 pfra_net;
	u_int8_t	 pfra_not;
	u_int8_t	 pfra_fback;
	u_int8_t	 pfra_type;
	u_int8_t	 pad[7];
};
#define pfra_ip4addr    pfra_u._pfra_ip4addr
#define pfra_ip6addr    pfra_u._pfra_ip6addr
.Ed
.It Dv DIOCRDELADDRS Fa "struct pfioc_table *io"
Delete one or more addresses from a table.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_addr
containing at least
.Vt pfrio_size
elements to delete from the table.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_addr .
On exit,
.Va pfrio_ndel
contains the number of addresses effectively deleted.
.It Dv DIOCRSETADDRS Fa "struct pfioc_table *io"
Replace the content of a table by a new address list.
This is the most complicated command, which uses all the structure members.
.Pp
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_addr
containing at least
.Vt pfrio_size
elements which become the new contents of the table.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_addr .
Additionally, if
.Va pfrio_size2
is non-zero,
.Va pfrio_buffer[pfrio_size..pfrio_size2]
must be a writeable buffer, into which the kernel can copy the
addresses that have been deleted during the replace operation.
On exit,
.Va pfrio_ndel ,
.Va pfrio_nadd ,
and
.Va pfrio_nchange
contain the number of addresses deleted, added, and changed by the
kernel.
If
.Va pfrio_size2
was set on entry,
.Va pfrio_size2
will point to the size of the buffer used, exactly like
.Dv DIOCRGETADDRS .
.It Dv DIOCRGETADDRS Fa "struct pfioc_table *io"
Get all the addresses of a table.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer[pfrio_size]
contains a valid writeable buffer for
.Vt pfr_addr
structures.
On exit,
.Va pfrio_size
contains the number of addresses written into the buffer.
If the buffer was too small, the kernel does not store anything but just
returns the required buffer size, without returning an error.
.It Dv DIOCRGETASTATS Fa "struct pfioc_table *io"
This call is like
.Dv DIOCRGETADDRS
but is used to get an array of
.Vt pfr_astats
structures.
.Bd -literal
struct pfr_astats {
	struct pfr_addr	 pfras_a;
	u_int64_t	 pfras_packets
			     [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
	u_int64_t	 pfras_bytes
			     [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
	time_t		 pfras_tzero;
};
.Ed
.It Dv DIOCRCLRASTATS Fa "struct pfioc_table *io"
Clear the statistics of one or more addresses.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_addr
containing at least
.Vt pfrio_size
elements to be cleared from the table.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_addr .
On exit,
.Va pfrio_nzero
contains the number of addresses effectively cleared.
.It Dv DIOCRTSTADDRS Fa "struct pfioc_table *io"
Test if the given addresses match a table.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_addr
containing at least
.Vt pfrio_size
elements, each of which will be tested for a match in the table.
.Vt pfrio_esize
must be the size of
.Vt struct pfr_addr .
On exit, the kernel updates the
.Vt pfr_addr
array by setting the
.Va pfra_fback
member appropriately.
.It Dv DIOCRSETTFLAGS Fa "struct pfioc_table *io"
Change the
.Dv PFR_TFLAG_CONST
or
.Dv PFR_TFLAG_PERSIST
flags of a table.
On entry,
.Va pfrio_buffer
must point to an array of
.Vt struct pfr_table
containing at least
.Vt pfrio_size
elements.
.Va pfrio_esize
must be the size of
.Vt struct pfr_table .
.Va pfrio_setflag
must contain the flags to add, while
.Va pfrio_clrflag
must contain the flags to remove.
On exit,
.Va pfrio_nchange
and
.Va pfrio_ndel
contain the number of tables altered or deleted by the kernel.
Yes, tables can be deleted if one removes the
.Dv PFR_TFLAG_PERSIST
flag of an unreferenced table.
.It Dv DIOCRINADEFINE Fa "struct pfioc_table *io"
Defines a table in the inactive set.
On entry,
.Va pfrio_table
contains the table ID and
.Va pfrio_buffer[pfrio_size]
contains an array of
.Vt pfr_addr
structures to put in the table.
A valid ticket must also be supplied to
.Va pfrio_ticket .
On exit,
.Va pfrio_nadd
contains 0 if the table was already defined in the inactive list
or 1 if a new table has been created.
.Va pfrio_naddr
contains the number of addresses effectively put in the table.
.It Dv DIOCXBEGIN Fa "struct pfioc_trans *io"
.Bd -literal
struct pfioc_trans {
	int		 size;	/* number of elements */
	int		 esize;	/* size of each element in bytes */
	struct pfioc_trans_e {
		int		type;
		char		anchor[MAXPATHLEN];
		u_int32_t	ticket;
	}		*array;
};
.Ed
.Pp
Clear all the inactive rulesets specified in the
.Vt pfioc_trans_e
array.
For each ruleset, a ticket is returned for subsequent "add rule" ioctls,
as well as for the
.Dv DIOCXCOMMIT
and
.Dv DIOCXROLLBACK
calls.
.Pp
Ruleset types, identified by
.Va type ,
can be one of the following:
.Pp
.Bl -tag -width PF_TRANS_RULESET -offset ind -compact
.It Dv PF_TRANS_RULESET
Filter rules.
.It Dv PF_TRANS_TABLE
Address tables.
.El
.It Dv DIOCXCOMMIT Fa "struct pfioc_trans *io"
Atomically switch a vector of inactive rulesets to the active rulesets.
This call is implemented as a standard two-phase commit, which will either
fail for all rulesets or completely succeed.
All tickets need to be valid.
This ioctl returns
.Er EBUSY
if another process is concurrently updating some of the same rulesets.
.It Dv DIOCXROLLBACK Fa "struct pfioc_trans *io"
Clean up the kernel by undoing all changes that have taken place on the
inactive rulesets since the last
.Dv DIOCXBEGIN .
.Dv DIOCXROLLBACK
will silently ignore rulesets for which the ticket is invalid.
.It Dv DIOCSETHOSTID Fa "u_int32_t *hostid"
Set the host ID, which is used by
.Xr pfsync 4
to identify which host created state table entries.
.It Dv DIOCOSFPFLUSH
Flush the passive OS fingerprint table.
.It Dv DIOCOSFPADD Fa "struct pf_osfp_ioctl *io"
.Bd -literal
struct pf_osfp_ioctl {
	struct pf_osfp_entry	fp_os;
	pf_tcpopts_t		fp_tcpopts;	/* packed TCP options */
	u_int16_t		fp_wsize;	/* TCP window size */
	u_int16_t		fp_psize;	/* ip->ip_len */
	u_int16_t		fp_mss;		/* TCP MSS */
	u_int16_t		fp_flags;
	u_int8_t		fp_optcnt;	/* TCP option count */
	u_int8_t		fp_wscale;	/* TCP window scaling */
	u_int8_t		fp_ttl;		/* IPv4 TTL */

	int			fp_getnum;	/* DIOCOSFPGET number */
};

struct pf_osfp_entry {
	SLIST_ENTRY(pf_osfp_entry) fp_entry;
	pf_osfp_t		fp_os;
	int			fp_enflags;
#define PF_OSFP_EXPANDED	0x001		/* expanded entry */
#define PF_OSFP_GENERIC		0x002		/* generic signature */
#define PF_OSFP_NODETAIL	0x004		/* no p0f details */
#define PF_OSFP_LEN	32
	u_char			fp_class_nm[PF_OSFP_LEN];
	u_char			fp_version_nm[PF_OSFP_LEN];
	u_char			fp_subtype_nm[PF_OSFP_LEN];
};
.Ed
.Pp
Add a passive OS fingerprint to the table.
Set
.Va fp_os.fp_os
to the packed fingerprint,
.Va fp_os.fp_class_nm
to the name of the class (Linux, Windows, etc),
.Va fp_os.fp_version_nm
to the name of the version (NT, 95, 98), and
.Va fp_os.fp_subtype_nm
to the name of the subtype or patchlevel.
The members
.Va fp_mss ,
.Va fp_wsize ,
.Va fp_psize ,
.Va fp_ttl ,
.Va fp_optcnt ,
and
.Va fp_wscale
are set to the TCP MSS, the TCP window size, the IP length, the IP TTL,
the number of TCP options, and the TCP window scaling constant of the
TCP SYN packet, respectively.
.Pp
The
.Va fp_flags
member is filled according to the
.In net/pfvar.h
include file
.Dv PF_OSFP_*
defines.
The
.Va fp_tcpopts
member contains packed TCP options.
Each option uses
.Dv PF_OSFP_TCPOPT_BITS
bits in the packed value.
Options include any of
.Dv PF_OSFP_TCPOPT_NOP ,
.Dv PF_OSFP_TCPOPT_SACK ,
.Dv PF_OSFP_TCPOPT_WSCALE ,
.Dv PF_OSFP_TCPOPT_MSS ,
or
.Dv PF_OSFP_TCPOPT_TS .
.Pp
The
.Va fp_getnum
member is not used with this ioctl.
.Pp
The structure's slack space must be zeroed for correct operation;
.Xr memset 3
the whole structure to zero before filling and sending to the kernel.
.It Dv DIOCOSFPGET Fa "struct pf_osfp_ioctl *io"
Get the passive OS fingerprint number
.Va fp_getnum
from the kernel's fingerprint list.
The rest of the structure members will come back filled.
Get the whole list by repeatedly incrementing the
.Va fp_getnum
number until the ioctl returns
.Er EBUSY .
.It Dv DIOCGETSRCNODES Fa "struct pfioc_src_nodes *psn"
.Bd -literal
struct pfioc_src_nodes {
	int	psn_len;
	union {
		caddr_t		psu_buf;
		struct pf_src_node	*psu_src_nodes;
	} psn_u;
#define psn_buf		psn_u.psu_buf
#define psn_src_nodes	psn_u.psu_src_nodes
};
.Ed
.Pp
Get the list of source nodes kept by sticky addresses and source
tracking.
The ioctl must be called once with
.Va psn_len
set to 0.
If the ioctl returns without error,
.Va psn_len
will be set to the size of the buffer required to hold all the
.Va pf_src_node
structures held in the table.
A buffer of this size should then be allocated, and a pointer to this buffer
placed in
.Va psn_buf .
The ioctl must then be called again to fill this buffer with the actual
source node data.
After that call,
.Va psn_len
will be set to the length of the buffer actually used.
.It Dv DIOCCLRSRCNODES
Clear the tree of source tracking nodes.
.It Dv DIOCIGETIFACES Fa "struct pfioc_iface *io"
Get the list of interfaces and interface drivers known to
.Nm .
All the ioctls that manipulate interfaces
use the same structure described below:
.Bd -literal
struct pfioc_iface {
	char			 pfiio_name[IFNAMSIZ];
	void			*pfiio_buffer;
	int			 pfiio_esize;
	int			 pfiio_size;
	int			 pfiio_nzero;
	int			 pfiio_flags;
};
.Ed
.Pp
If not empty,
.Va pfiio_name
can be used to restrict the search to a specific interface or driver.
.Va pfiio_buffer[pfiio_size]
is the user-supplied buffer for returning the data.
On entry,
.Va pfiio_size
contains the number of
.Vt pfi_kif
entries that can fit into the buffer.
The kernel will replace this value by the real number of entries it wants
to return.
.Va pfiio_esize
should be set to
.Li sizeof(struct pfi_kif) .
.Pp
The data is returned in the
.Vt pfi_kif
structure described below:
.Bd -literal
struct pfi_kif {
	char				 pfik_name[IFNAMSIZ];
	RB_ENTRY(pfi_kif)		 pfik_tree;
	u_int64_t			 pfik_packets[2][2][2];
	u_int64_t			 pfik_bytes[2][2][2];
	time_t				 pfik_tzero;
	int				 pfik_flags;
	int				 pfik_flags_new;
	void				*pfik_ah_cookie;
	struct ifnet			*pfik_ifp;
	struct ifg_group		*pfik_group;
	int				 pfik_states;
	int				 pfik_rules;
	int				 pfik_routes;
	TAILQ_HEAD(, pfi_dynaddr)	 pfik_dynaddrs;
};
.Ed
.It Dv DIOCSETSTATUSIF Fa "struct pfioc_iface *pi"
Specify the interface for which statistics are accumulated.
.It Dv DIOCSETIFFLAG Fa "struct pfioc_iface *io"
Set the user settable flags (described above) of the
.Nm
internal interface description.
The filtering process is the same as for
.Dv DIOCIGETIFACES .
.Bd -literal
#define PFI_IFLAG_SKIP	0x0100	/* skip filtering on interface */
.Ed
.It Dv DIOCCLRIFFLAG Fa "struct pfioc_iface *io"
Works as
.Dv DIOCSETIFFLAG
above but clears the flags.
.It Dv DIOCKILLSRCNODES Fa "struct pfioc_src_node_kill *psnk"
Explicitly remove source tracking nodes.
.Bd -literal
struct pfioc_src_node_kill {
	sa_family_t		 psnk_af;
	struct pf_rule_addr	 psnk_src;
	struct pf_rule_addr	 psnk_dst;
	u_int			 psnk_killed;
};
.Ed
.El
.Sh FILES
.Bl -tag -width /dev/pf -compact
.It Pa /dev/pf
packet filtering device.
.El
.Sh EXAMPLES
The following example demonstrates how to use the
.Dv DIOCGETLIMIT
command to show the hard limit of a memory pool used by the packet filter:
.Bd -literal
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <net/if.h>
#include <net/pfvar.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>

static const struct {
	const char	*name;
	int		index;
} pf_limits[] = {
	{ "states",		PF_LIMIT_STATES },
	{ "src-nodes",		PF_LIMIT_SRC_NODES },
	{ "frags",		PF_LIMIT_FRAGS },
	{ "tables",		PF_LIMIT_TABLES },
	{ "table-entries",	PF_LIMIT_TABLE_ENTRIES },
	{ NULL,			0 }
};

void
usage(void)
{
	extern char *__progname;
	int i;

	fprintf(stderr, "usage: %s [", __progname);
	for (i = 0; pf_limits[i].name; i++)
		fprintf(stderr, "%s%s", (i > 0 ? "|" : ""), pf_limits[i].name);
	fprintf(stderr, "]\en");
	exit(1);
}

int
main(int argc, char *argv[])
{
	struct pfioc_limit pl;
	int i, dev;
	int pool_index = -1;

	if (argc != 2)
		usage();

	for (i = 0; pf_limits[i].name; i++)
		if (!strcmp(argv[1], pf_limits[i].name)) {
			pool_index = pf_limits[i].index;
			break;
		}

	if (pool_index == -1) {
		warnx("no such memory pool: %s", argv[1]);
		usage();
	}

	dev = open("/dev/pf", O_RDWR);
	if (dev == -1)
		err(1, "open(\e"/dev/pf\e") failed");

	bzero(&pl, sizeof(struct pfioc_limit));
	pl.index = pool_index;

	if (ioctl(dev, DIOCGETLIMIT, &pl))
		err(1, "DIOCGETLIMIT");

	printf("The %s memory pool has ", pf_limits[i].name);
	if (pl.limit == UINT_MAX)
		printf("unlimited entries.\en");
	else
		printf("a hard limit of %u entries.\en", pl.limit);

	return (0);
}
.Ed
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr bridge 4 ,
.Xr pflog 4 ,
.Xr pflow 4 ,
.Xr pfsync 4 ,
.Xr pf.conf 5 ,
.Xr pfctl 8
.Sh HISTORY
The
.Nm
packet filtering mechanism first appeared in
.Ox 3.0 .
